         [:p [:span {:class (str "metric " (name css-class))} value]
             [:span {:class "label"} label]]]]]))
 
+(defn- format-delta
+  "Create a display fragment for a delta value."
+  
+  ([delta prior-date]
+  (let [pos (when (pos? delta) "+")]
+    (str "(" pos (if (zero? delta) "no change" (utils/with-size-label delta)) "% since " prior-date ") ")))
+  
+  ([currency delta prior-date]
+  (str "(" (if (zero? delta) "no change" (utils/with-currency currency (utils/with-size-label delta) true))
+    " since " prior-date ") ")))
+
 (defn- growth-metric [periods metadata currency]
   (let [growth-metric (first periods)
         slug (:slug growth-metric)

      [:tr
        (into [:td]
          (map #(growth-metric % metadata currency) periods))]]))

(defn- format-delta
  "Create a display fragment for a delta value."
  
  ([delta prior-date]
  (let [pos (when (pos? delta) "+")]
    (str "(" pos (if (zero? delta) "no change" (utils/with-size-label delta)) "% since " prior-date ") ")))
  
  ([currency delta prior-date]
  (str "(" (if (zero? delta) "no change" (utils/with-currency currency (utils/with-size-label delta) true))
    " since " prior-date ") ")))

(defn- finance-metrics [topic currency]
  (let [sorted-finances (reverse (sort-by :period (:data topic)))

        date (when (and interval period) (utils/format-period interval period))
        value (:value growth-metric)
        ;; Check for older periods contiguous to most recent
        contiguous-periods (when (seq periods) (utils/contiguous (map :period periods) (keyword interval)))
        prior-contiguous? (>= (count contiguous-periods) 2)
        ;; Info on prior period
        prior-metric (when prior-contiguous?
